This application claims priority from Japanese Patent Application Reference No. 11-264164, filed Sep. 17, 1999.
The present invention relates to a method and device for inspecting particles and defects that occur on a specimen such as a semiconductor wafer in a semiconductor production process.
Semiconductor devices are produced by performing a plurality of processes such as exposure, development, etching, and the like on a wafer, which serves as a substrate. A particle inspection device or pattern inspection device is used after predetermined processes out of this plurality of processes in order to inspect the positions and sizes of particles and defects on the wafer. Using an optical microscope or an SEM (scanning electron microscope), magnified images are manually generated for some or all of the particles and defects detected by the inspections. This provides detailed information such as sizes, shapes, and textures (surface patterns), and helps to determine the process in which the particles and defects were generated.
Recent years have seen the development of devices for generating magnified images equipped with ADR (auto defect review), which is a feature for automatically obtaining magnified images of particles and defects based on inspection data from particle inspection devices and pattern inspection devices.
As described above, ADR is performed using inspection data from particle inspection devices and pattern inspection devices. Due to noise and the like, the inspection data from these inspection devices often contains significant amounts of false alarm (e.g., a non-existent defect is reported). Attempting to increase inspection precision will increase the false alarm. In such cases, ADR will obtain a large number of images that do not contain defects, thus resulting in wasted inspection time.
Also, due to differences in the inspection systems, a defect detected by a particle detection device or a pattern inspection device may not be detected by a details inspection device. For example, if the details inspection device is an SEM, particles present under a transparent layer formed on the wafer will not be observable. As with the case above, ADR will result in images where particles and defects cannot be observed or images in which particles and defects are not present, thus resulting in wasted inspection time.
With manual observations, if viewing a particle or defect using a front view image is difficult, the imaging conditions can be adjusted, e.g., by varying the observation angle.
However, with ADR, imaging conditions cannot be changed according to characteristics of particles and impurities. Thus, images that provide the information needed for analysis may not be possible. This will also lead to wasted inspection time.
The object of the present invention is to eliminate the problems of the conventional technology and to provide an inspection method and device that implements improved efficiency and effectiveness in inspection of details.
The method for inspecting specimens according to the present invention is a method for inspecting defects in the specimen in which detailed inspections performed on defects detected by a defect inspection process are controlled on the basis of information relating to the defects. In the defect inspecting process, position information of defects on the specimen is obtained, and attribute information indicating characteristics of the defects for which the defect position information was acquired is added. In the detailed inspection process, the inspection positions are determined based on the position information and detailed inspection is performed based on the attributes.
The attribute information can include: defect characteristics obtained from relative positioning of defect position information obtained by the defect inspection process; defect attribute information obtained by inspecting defects based on the defect position information using means for optical detection; or comparing defect position information obtained by the defect inspecting process with defect position information obtained from a defect inspecting process from another process.
Furthermore, the attribute information according to the present invention can include information indicating whether or not a defect is on the surface of the specimen or whether or not detailed inspection is to be performed on the defect.
A specimen inspection device according to the present invention includes: means for detecting defects that detects defects on the specimen; means for adding attributes that adds attribute information to the defects; means for storing that stores attribute information; and means for performing detailed inspection that performs detailed inspection of defects based on the attribute information.
Alternatively, the specimen inspection device according to the present invention can include: means for detecting defects that defects defects on a semiconductor wafer that serves as the specimen; means for evaluating that evaluates whether the defects detected by the defect detecting means is on the surface of the semiconductor wafer or below the surface; means for storing that store information relating to coordinates of the defects detected by the defect detecting means and evaluation results from the evaluating means; and mean for outputting that outputs information relating to coordinates of the defects, detected by the defect detecting means and evaluation results from the evaluating means stored in the storing means.
Having the structures described above, the defect inspecting method of the present invention can determine whether or not each defect detected on the specimen should have a detailed inspection performed based on the attributes added to the defect. This allows detailed inspections to be performed reliably only for the defects that require detailed inspections, thus eliminating needless detailed inspections and improving detailed inspection efficiency and reducing the time involved.
Also, according to the present invention, imaging conditions in the detailed inspection can be set up beforehand based on the attributes added to the defects and particles. This allows imaging conditions for detected defects and particles to be varied according to their attributes, thus providing images that can be easily studied based on the type of particle or defect. By setting up conditions suited for image processing, stable image processing results can be provided.
These and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.